This invention relates to infusion packages and the method by which they are made. More particularly, the invention relates to improved infusion packages that have a flattened configuration for packing and a stable, unflattened or three-dimensional, expanded configuration that provides a large volume interior for better, more effective contact between liquid and fill.
Increased surface area contact between a liquid and infusible solids speeds infusion. Movement of the liquid over and about the surfaces of the solids results in faster infusion. Prior art infusion packages have not had interiors with enlargeable volumes adequate to loosely contain the infusible fill and to thereby give improved surface area contact and better passage of liquid into and out of the mass of wet fill.
The most familiar infusion package is the ordinary tea bag. The single compartment or "pillow" tea bag is a flat bag of liquid pervious material that contains enough tea for a single serving. Of itself, the bag has no internal volume. Only the presence of fill, that is to say the tea, spreads the envelope's sides to give the bag volume to accommodate the contents. As is well known in the art, tea swells when wet. It forms a swollen compacted mass that may fill or nearly fill the conventional single envelope bag. Even if abundant space is left in the bag, the natural flat disposition of the envelope tends to keep the tea compacted. The swelling tea presses outwardly against the inside walls of the envelope which are constrained by linear upper and lower seams and linear side edges. Penetration by the liquid into and through the mass of tea is limited. Infusion or steeping occurs primarily through the envelope sides where they separate the surface of the swollen tea mass from the water. Stirring the tea or dunking the bag speeds infusion by interrupting the tendency of the liquid inside and outside the bag to reach equilibrium near the bag sides.
Some prior art suggests pleats or the like to accommodate the swelling of the tea when the bag is immersed. The pleats in the bag accommodate the swelling of the tea. Often these bags have only a naturally flat disposition against which the swelling tea must act to cause expansion of the bag. The volume to which the bag expands is only that demanded by the swelling of the tea. No excessive volume that would permit looseness of the tea mass and easy flowing of water about the leaf particles would seem to result.
Prior art infusion packages with two or more fill containing segments did increase the surface area of infusible fill exposed to liquid through the side of the package. The art is replete with tea bags divided into several tea-containing sections. Providing connected segments that permitted liquid flow between the segments exposed more bag surface area to liquid for extraction therethrough. It is true that these bags improved brewing, but in each segment, the mass of tea compacts as it swells against the sides of each individual segment, and even though there is more surface tea, there is little opportunity for liquid to flow in and about tea particles in the center of the mass.